Two-particle self-consistent approximation, pseudogap and superconductivity in the attractive Hubbard model

Details Two-particle self-consistent approximation, pseudogap and superconductivity in the attractive Hubbard model Two-particle self-consistent approximation, pseudogap and superconductivity in the attractive Hubbard model

2000-12-15

arxiv.org/abs/cond-mat/0012301v1

Physics

Condensed Matter

Strongly Correlated Electrons

TeX, thesis, 127 pages, 20 figures (in French)

Scientific paper

In this thesis, I present a non-perturbative approach to the single-band attractive Hubard model which is an extension of previous work by Vilk and Tremblay on the repulsive model. Exact results are derived in the general context of functional derivative approaches to many-body theories. The first step of the approximation is based on a local field type ansatz. All physical quantities can be expressed as a function of double-occupancy (in addition to temperature and filling). Double-occupancy is determined without adjustable parameter by imposing the Pauli principle and a crucial sum-rule, making the first step of the approximation Two-Particle Self-Consistent. The final expression for the self-energy is obtained by calculating the low-frequency part of the exact expression with the two-particle correlation, Green function and renormalized vertex obtained in the first step of the approximation. The Mermin-Wagner theorem in two dimensions is automatically satisfied. Application of this non-perturbative many-body approach to the intermediate coupling regime shows quantitative agreement with quantum Monte Carlo calculations. Both approaches predict the existence of a pseudogap in the single-particle spectral weight. I present some physical properties, such as correlation lengths, superfluid density, and characteristic pair fluctuation energy, to highlight the origin of the pseudogap in the weak to intermediate coupling regime. These results suggest that two-dimensional systems that are described by a symmetry group larger than SO(2) could have a larger region of pseudogap behavior. High-temperature superconductors may belong to that category of systems.

Affiliated with

Also associated with

No associations

Rating

Two-particle self-consistent approximation, pseudogap and superconductivity in the attractive Hubbard model does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Two-particle self-consistent approximation, pseudogap and superconductivity in the attractive Hubbard model, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Two-particle self-consistent approximation, pseudogap and superconductivity in the attractive Hubbard model will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-296462